With my software a project has to be running at one sample rate.
When I import a file the program changes it to the right sample rate.
Sound forge can play both 44.1 and 48k when they system is running at 48k but will not play either if the system is running at the higher rates. That was kind of a hassle running the higher rates, I couldn't listen to the final output till I changes the audio sample rate of my interface.
I've been running 48k for some time now, I think it adds a little something to the quality.
I tried higher rates but it puts too much strain on my equipment. I give up the extra quality for ease of workflow.
Some people swear by 44.1 all the way type of methodology.
When I export my finished mix I dither to take it down from 24 to 16 bits but I leave it at 48k then when I take the exported file into sound forge (my sort of mastering program) I compress it then save it as a wma which is 44.1.
The output I'm getting fits my needs.
Looking at your needs.
Some say you use 44.1k for music and 48k for video.
If it works for you then it's right.